Posted Today 11H 41M ago
Zinc is a terrible metal to make coins from, because it corrodes so easily. Nevertheless, it's entirely possible for zinc to remain open to the air, and even exposed in circulation, and not spontaneously disintegrate or dissolve. The Nazis made pure zinc coins to circulate in both Germany and their occupied territories, and many of those coins are still in collectable condition, 80 years later - they may be ugly, black, or dull grey, but not corroded.
Fundamentally, it is moisture, rather than oxygen, that causes the damaging blistery corrosion which zincolns are famous for. Coins in circulation with splits or flaws in the plating are doomed because they're constantly getting exposed to moisture, from condensation, people's hands, or simple rainwater. Slabs are usually pretty good at minimizing exposure to moisture and oxidation more generally, especially if due care is taken in the storage of the slabs.
In other words, the exposed zinc is only slightly more reactive than the exposed copper. If you're trusting the slab to preserve the bright orange glow of red copper, then it's just as trustworthy to keep the zinc shiny and fresh too.
Long term, of course, you are correct - the planet will eventually reclaim these coins and turn their shiny metals back into the minerals from whence they originally came, and this will inevitably happen, whether the plating is breached or not. But in a slab, locked away so the planet can't get at it, that process could take centuries.
Fundamentally, it is moisture, rather than oxygen, that causes the damaging blistery corrosion which zincolns are famous for. Coins in circulation with splits or flaws in the plating are doomed because they're constantly getting exposed to moisture, from condensation, people's hands, or simple rainwater. Slabs are usually pretty good at minimizing exposure to moisture and oxidation more generally, especially if due care is taken in the storage of the slabs.
In other words, the exposed zinc is only slightly more reactive than the exposed copper. If you're trusting the slab to preserve the bright orange glow of red copper, then it's just as trustworthy to keep the zinc shiny and fresh too.
Long term, of course, you are correct - the planet will eventually reclaim these coins and turn their shiny metals back into the minerals from whence they originally came, and this will inevitably happen, whether the plating is breached or not. But in a slab, locked away so the planet can't get at it, that process could take centuries.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis
